1. Field of the Invention
This invention relates to a means for controlling the speed of vehicles in selected zones such as school and hospital zones, and more particularly, to a retractable speed bump which is mounted in the road, street or roadway and is operable to selectively raise and lower a cap member or block above street level by means of an internally mounted hydraulic cylinder to provide an impediment to the rapid movement of a vehicle over the roadway. The speed bump is designed to present an elevated, square or rectangularly-shaped obstacle which projects above the surface of the road or street to cause severe bumping or jolting of a vehicle when the vehicle tires strike the obstacle at a high rate of speed. The retractable speed bump of this invention may be remotely controlled, and in a preferred embodiment, is characterized by a generally rectangular encasement which is recessed in the road surface and contains upper and lower wedge-shaped members which slidably cooperate along inclined planes of contact with each other and with the floor and walls of the encasement by means of friction-reducing means such as ball bearings. The wedge-shaped members are relatively movable by operation of a hydraulic cylinder attached to the encasement wall and the lower wedge-shaped member to effect raising and lowering of the top portion of the upper member above the surface of the roadway. The retractable speed bump of this invention can be constructed of any width and length necessary to accommodate substantially any road, street or roadway, and may be installed as a single entity or as multiple assemblies, depending upon the extent of traffic control desired.
2. DESCRIPTION OF THE PRIOR ART
Prior art devices for controlling speed of traffic in selected zones are varied in design. Typical of such devices is the "Pop Up Traffic Divider" disclosed in U.S. Pat. No. 3,530,775 to Joseph W. Bowersox. The traffic divider featured in this patent includes a housing which is buried flush with the highway and contains a casing having a column supported on the casing bottom and flush with the highway at the top. An annular piston is disposed between the casing and the column and is moved up and down by differential pressure of fluid such as air. A resilient, deformable tube is mounted on the piston and is retracted within, and expelled from the casing by movement of the piston. The upper end of the column and the casing present a rounded body or bodies, over which the extended, deformable and resilient tube can be bent without injury. Another device which is desiged to be selectively raised and lowered in the roadway is the "Roadway Safety Device" disclosed in U.S. Pat. No. 3,134,184 to E. Neblett. This device is primarily intended to warn of one-way streets and avenues, and includes a hinged plate provided with warning indicia on the side opposite the hinge, with a spring mechanism beneath the hinge to effect raising and lowering of the device with respect to the road surface. Another device for controlling the speed of vehicular traffic is disclosed in U.S. Pat. No. 3,720,181, to Jack D. Elkins, and is entitled, "Inflatable Warning Device for Roadways." The Elkins device generally comprises an elongated, inflatable warning mechanism which is removably disposed transversely of a roadway during selected periods of time in order to control the speed of vehicles traversing the road. Permanently installed vehicular speed control devices are also known in the prior art, and are typified by U.S. Pat. No. 4,012,156 to William Turner. Mr. Turner's "Retractable Safety Speed Bump" includes an elongated half cylinder, hinged to and normally resting in nested configuration in a half cylinder-shaped receptacle disposed in the surface of the roadway, and adapted to hingedly swing upwardly and rearwardly against the roadway to present a curved protuberance on the surface of the road.
In addition to the mechanical devices disclosed in the above described patents, a commonly used method of controlling the speed of vehicular traffic in certain areas is the use of permanently mounted blocks or projections cemented to the road surface, usually in staggered arrays. While these projections are relatively inexpensive, they are susceptible of being broken and displaced from their anchored position by breaking the bond attaching them to the roadway due to the repetitive loads sustained by multiple contacts with the tires of passing vehicles, and they are not susceptible of being removed during periods of minimum traffic or at times when speed control of passing vehicles is unnecessary. Such devices have therefore frequently become not only an eye sore, but also a nuisance during non-regulatory time periods.
Accordingly, it is an object of this invention to provide a retractable speed bump which can be either manually or automatically and remotely activated to a raised and functional position above the surface of a road, street or roadway when its use is necessary to control the speed of vehicular traffic, and subsequently retracted to an elevation co-extensive with the roadway surface when there is no longer a necessity for controlling the traffic speed.
Another object of this invention is to provide a new and improved retractable speed bump which is automatically or manually controlled by a hydraulic cylinder and includes a pair of wedge-shaped blocks slidably mounted in an encasement and fitted in the road or street to present a smooth, unimpeded extension of the street when in retracted configuration, and a projecting, speed-interrupting surface when in selectively extended configuration.
Another object of this invention is to provide a permanently-mounted, retractable speed bump which is normally recessed in the surface of a roadway, road or street requiring vehicular traffic control, and which is characterized by a hydraulic cylinder, the cylinder or base of which is mounted in an encasement or pit, and piston of which is attached to a lower wedge-shaped block which interferes with an upper, upwardly extending block along matching, inclined faces, wherein a portion of the upper block is caused to project vertically above the road surface when the hydraulic cylinder is activated and the lower block is slidably disposed horizontally away from the cylinder base.
Yet another object of this invention is to provide a new and improved retractable speed bump which can be mounted in recessed fashion in an enclosure or pit in the roadway, road or street surface, and which includes a bottom block having an upward standing inclined face and resting on the bottom of the enclosure or pit, and a top block having a matching, downwardly facing inclined face and carried by the bottom block, and at least one hydraulic cylinder mounted in one wall of the enclosure and having a piston cooperating with the bottom block to effect horizontal slidable displacement of the bottom block in the enclosure and vertical movement of the top block upwardly from a position normally in registration with the street surface to a position with a portion of the top block projecting above the street surface.
A still further object of the invention is to provide a retractable speed bump mounted in a roadway for controlling the speed of vehicles, which includes a generally rectangularly-shaped encasement containing upper and lower, relatively movable, wedge-shaped members slidably fitted in the encasement and configured to cooperate by means of friction-reducing means, such as ball bearings, in adjacent, inclined faces to selectively raise the top of the upper member above street or road level responsive to activation of a hydraulic cylinder attached to the encasement and the lower member.